Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In


Check Out

Supplement Supercharge

Put the pep back in your step with L-carnitine

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

If you’re feeling lethargic, L-carnitine can help. The nutrient, sometimes called simply carnitine, enables our heart and other muscles to make energy, eliminate toxic by-products, and continue to function well as we live longer. Our bodies make L-carnitine from the amino acids lysine and methionine, found in proteins, but we don’t always produce enough-especially when faced with physical challenges such as exercise or anything that stresses the heart, including diabetes and heart disease. Plus, our natural ability to produce L-carnitine decreases as we get older.

How It Works

Each of our cells contains mitochondria, tiny components that generate energy. They’re like microscopic furnaces that use fatty acids as fuel. L-carnitine acts as a cargo train, transporting the fatty acids to the mitochondria and taking away the trash-by-products of the process that would be toxic if left in the cell. Without sufficient L-carnitine, mitochondria can’t function optimally, and energy suffers.

Mitochondria also play a key role in aging because they contain their own DNA, separate from the overall cell. According to studies published in the Journal of the American Medical Association and other scientific publications, mitochondrial DNA influences cell regeneration and death. And if that DNA is damaged, cells don’t function as they should-they may die prematurely or mutate-and the aging process accelerates. Keeping mitochondria healthy is considered one of the key strategies for longevity, and L-carnitine is a necessary ingredient.

Proven Benefits

Studies have shown that L-carnitine helps the heart work more efficiently. For example, research presented at a conference sponsored by the National Institutes of Health in Bethesda, Md., included these findings:

  • The heart is dependent on L-carnitine because fatty acids are the major source of energy for the heart muscle.
  • Studies of more than 2,500 patients who suffered a heart attack found that L-carnitine significantly reduced deaths, chest pain, and shortness of breath; improved recovery; and lowered the odds of developing heart failure.
  • In patients with chronic heart failure, research at 49 centers in eight European countries found that L-carnitine improved the ability to walk and do physical exercise.

Other research findings include:

  • A study published in Metabolism: Clinical and Experimental concluded that L-carnitine helps middle-aged people recover better from exercise. Other research has found similar benefits among younger people.
  • A study of pregnant women, published in the Journal for Obstetrics and Gynecology, found that 2 grams daily of L-carnitine reduced the incidence of gestational diabetes. Levels of L-carnitine typically drop during pregnancy, and may contribute to diabetes risk.
  • A review of numerous studies published in Alternative Medicine Review, found that a specific form of L-carnitine, acety-L-carnitine, improved mental function among people with Alzheimer’s. It also reduced symptoms of depression and ADHD; helped relieve neuropathy caused by diabetes, chemotherapy, or HIV drug therapy; helped the brain recover from oxygen deprivation; and, taken in combination with L-carnitine, improved male fertility.

L-Carnitine and Drugs

Two types of drugs may work better with L-carnitine: Cholesterol-lowering statins and medications that lower blood sugar for type 2 diabetics. Studies used 2 grams daily of L-carnitine with a statin, and 1 gram twice daily of acety-L-carnitine with diabetes drugs.

Other studies show that L-carnitine may reduce side effects of AZT, used to treat HIV or AIDs, as well as doxorubicin, a type of chemotherapy for cancer.

Shopping Guide

L-carnitine can be found in food, chiefly red meats, but not in sufficient quantities to produce therapeutic effects. Most studies have found that beneficial doses of L-carnitine range from 1-3 grams daily. To obtain just 1 gram, you would need to eat about 2.3 lbs. of beef each day! So supplements are definitely the way to go.

L-carnitine isn’t a stimulant, so it doesn’t cause jitters or other caffeine-like effects. It’s absorbed more efficiently on an empty stomach, but if you experience discomfort, take it with a meal of carbohydrates and fats, as the amino acids in proteins will compete for absorption.If you are healthy, take 500 mg once or twice daily.

If you have diabetes, prediabetes, or heart disease, take up to 3 g daily in divided doses. Start with a lower dose and increase gradually.

Go Shopping!

Bluebonnet liquid l-carnitine (Carnipure) in Natural Vanilla Flavor is an easy-to-swallow form of the amino acid that can easily be added to smoothies or juice. Also available in raspberry and orange flavors.

NOW Foods l-carnitine delivers 500 mg of Carnipure L-carnitine per tablet. This formula is 100 percent vegetarian and free of common allergens, including gluten, corn, soy, milk, and eggs.

One capsule of Source naturals l-carnitine gives you 500 mg of Carnipure, a proprietary and high-quality form of L-carnitine. Source Naturals also offers the amino acid in other strengths (e.g., 250 mg).